Gas Gun Seating Depth

[TennJed]

Hi Folks,

Wondering if anyone has tried different seating depths for gas guns (like we do with bolt guns) and what are the results? I know combustion is critical, but again wondering about seating depth, haven't played with it yet. Working on a 6ARC but I don't care what calibers have been used, just looking for real world info from experienced people.

Thank you

 

[Eric H]

Hi Folks,

Wondering if anyone has tried different seating depths for gas guns (like we do with bolt guns) and what are the results? I know combustion is critical, but again wondering about seating depth, haven't played with it yet. Working on a 6ARC but I don't care what calibers have been used, just looking for real world info from experienced people.

Thank you

Currently doing development for a 6MM Predator/Grendel. Looked in Hodgdon load data but nothing for the bullet I'm running. Loaded it to MAG length and went for it. I was already over max pressure when I found a fairly decent group but wanted it closer so started going away from the L/G and groups got better. There was a tradeoff where the further from L/G the.slower the round. Currently at a comfortable .369MOA in 2700's FPS.

 

[C.O. Shooter]

Going through this now. Definitely different than a bolt gun.

 

[Eric H]

Going through this now. Definitely different than a bolt gun.

Just ensure your.pressure is high enough to cycle the spent casing. You gonna go through some brass. ARs are brutal on brass.

 

[C.O. Shooter]

My first 30 new Lapua brass weren't bad at all no issues. All 3pm ejections.

 

[Pdyson]

I definitely do. I start at mag length and work back. Most heavy loads in my ARC perform best very close to mag length. I have to go much shorter with the 75g because they are short and get wonky seated long. I hunt suppressed but for competition shooting the EC tuner brake works like magic.

 

[Pdyson]

I definitely do. I start at mag length and work back. Most heavy loads in my ARC perform best very close to mag length. I have to go much shorter with the 75g because they are short and get wonky seated long. I hunt suppressed but for competition shooting the EC tuner brake works like magic.

By the way you can get false pressure signs with short gas tubes. The bolt unlocks before the pressure falls and the bolt swipes the case head. Rifle + 1 or 2 will reduce the swipes.

 

[TennJed]

Currently doing development for a 6MM Predator/Grendel. Looked in Hodgdon load data but nothing for the bullet I'm running. Loaded it to MAG length and went for it. I was already over max pressure when I found a fairly decent group but wanted it closer so started going away from the L/G and groups got better. There was a tradeoff where the further from L/G the.slower the round. Currently at a comfortable .369MOA in 2700's FPS.

Thank you

 

[TennJed]

Just ensure your.pressure is high enough to cycle the spent casing. You gonna go through some brass. ARs are brutal on brass.

Thank you

 

[TennJed]

By the way you can get false pressure signs with short gas tubes. The bolt unlocks before the pressure falls and the bolt swipes the case head. Rifle + 1 or 2 will reduce the swipes.

Thank you